Vietnam or Cambodia this Summer?

Hi,

41Y M here. In a position to solo travel after a long time with approx.2 uninterrupted free weeks in Jul/Aug.

I solo travelled in Thailand back in 2008 and I absolutely loved it. Thinking about going back to SE Asia and am thinking about Vietnam and Cambodia.

I understand that the season might not be great - especially Vietnam. Lonely planet explicitly says heat + rain + crowds of locals.

Conversely, Cambodia is actually recommended for less crowds and lush green everywhere.

Flights are about the same cost.

What's your experience? Any recommendations or considerations?

My travel style: move around, explore, see, taste, experience. Nature, sights and see and beaches as well.

I don't like to spend too much time in big cities when I travel like this.